1. Technical Field
The invention relates to the storage of information. More particularly, the invention relates to a stream-oriented interconnect for networked computer storage.
2. Description of the Prior Art
The properties of typical traffic between computing devices and storage devices are fundamentally different from those of the typical flows between computing devices. For example, the latency between the time a request is issued for a disk read and/or write operation and the time the operation is performed by the disk can run into the multiple milliseconds due to factors such as disk seek time and disk rotational delays. As opposed to typical Internet traffic, which tends to have short bursts of traffic to different servers, the traffic in a storage network tends to have significantly longer packets and, in many cases, is stream (circuit) oriented and predictable. In addition, while in general it is very important to minimize the latency in computer networks, the latency of write-to-disk operations is relatively unimportant in many cases.
Known stream-oriented switches, e.g. optical interconnects based on micro-mirrors, electro-optic, thermo-optic, acousto-optic, bubbles, etc., are capable of very high throughput but have relatively long switching/reconfiguration times. Conversely, conventional electronic packet switches have lower maximum throughput than optical switches, but have significantly faster switching times. Switching time, as used herein, refers to the time that elapses between a command to create a connection between ports and the time when the data can start flowing through the system.
It would be advantageous to provide an apparatus and method for connecting a plurality of computing devices, e.g. web servers, database servers, etc., to a plurality of storage devices, such as disks, disk arrays, tapes, etc., by using a stream-oriented (circuit oriented) switch that has high throughput, but that requires non-negligible time for reconfiguration.